Question

每当它检测到声音（超过特定阈值）时，我都需要从树莓派中以PCM文件格式记录音频，并在它变得无声时停止播放。因此，我遇到了一个先前提出的问题，并遵循了Detect & Record Audio in Python中的最高答案。但是，它以WAV格式保存文件，但是我使用的API仅读取pcm，speex或speex-wb格式。

如何以pcm格式记录音频，同时保持仅在检测到声音时才进行记录的功能？

from sys import byteorder
from array import array
from struct import pack

import pyaudio
import wave

THRESHOLD = 8000
chans = 1
chunk = 4096
form_1 = pyaudio.paInt16
samp_rate = 44100
dev_index = 2 # device index found by p.get_device_info_by_index(ii)
wav_output_filename = 'test4.wav'

def is_silent(snd_data):
    "Returns 'True' if below the 'silent' threshold"
    return max(snd_data) < THRESHOLD

def normalize(snd_data):
    "Average the volume out"
    MAXIMUM = 16384
    times = float(MAXIMUM)/max(abs(i) for i in snd_data)

    r = array('h')
    for i in snd_data:
        r.append(int(i*times))
    return r

def trim(snd_data):
    "Trim the blank spots at the start and end"
    def _trim(snd_data):
        snd_started = False
        r = array('h')

        for i in snd_data:
            if not snd_started and abs(i)>THRESHOLD:
                snd_started = True
                r.append(i)

            elif snd_started:
                r.append(i)
        return r

    # Trim to the left
    snd_data = _trim(snd_data)

    # Trim to the right
    snd_data.reverse()
    snd_data = _trim(snd_data)
    snd_data.reverse()
    return snd_data

def add_silence(snd_data, seconds):
    "Add silence to the start and end of 'snd_data' of length 'seconds' (float)"
    silence = [0] * int(seconds * samp_rate)
    r = array('h', silence)
    r.extend(snd_data)
    r.extend(silence)
    return r

def record():
    """
    Record a word or words from the microphone and 
    return the data as an array of signed shorts.

    Normalizes the audio, trims silence from the 
    start and end, and pads with 0.5 seconds of 
    blank sound to make sure VLC et al can play 
    it without getting chopped off.
    """
    audio = pyaudio.PyAudio()
    stream = audio.open(format = form_1, channels=chans, rate = samp_rate,
                    input_device_index = dev_index, input = True, #output=True,
                    frames_per_buffer = chunk)

    num_silent = 0
    snd_started = False

    r = array('h')

    while 1:
        # little endian, signed short
        snd_data = array('h', stream.read(chunk, exception_on_overflow = False))
        if byteorder == 'big':
            snd_data.byteswap()
        r.extend(snd_data)

        silent = is_silent(snd_data)

        if silent and snd_started:
            num_silent += 1
        elif not silent and not snd_started:
            snd_started = True

        if snd_started and num_silent > 30:
            break

    sample_width = audio.get_sample_size(form_1)
    stream.stop_stream()
    stream.close()
    audio.terminate()

    r = normalize(r)
    r = trim(r)
    r = add_silence(r, 0.5)
    return sample_width, r

def record_to_file(path):
    "Records from the microphone and outputs the resulting data to 'path'"
    sample_width, data = record()
    data = pack('<' + ('h'*len(data)), *data)

    wf = wave.open(path, 'wb')
    wf.setnchannels(chans)
    wf.setsampwidth(sample_width) #
    wf.setframerate(samp_rate)
    wf.writeframes(data) #
    wf.close()

if __name__ == '__main__':
    print("please speak a word into the microphone")
    record_to_file(wav_output_filename)
    print("done - result written to " + wav_output_filename)

Answer 1

我找不到将音频文件格式化为pcm的任何解决方案，但是我发现我能够以16k的采样率处理wav格式的音频。所以我将保留它。

用Python检测并记录音频为PCM格式

1 个答案: